Hundreds of thousands of supporters of Ali Abdullah Saleh cheered on as the former Yemeni president promised to send thousands of fighters to the front lines in a defiant speech a day after his supposed Houthi allies called him a "traitor".

The rally marking 35 years since the founding of Saleh's Arab nationalist General People's Congress sends out a signal that the strongman remains a force to be reckoned with.

"We are ready to fill the fronts with thousands of fighters and they are ready to go," said Saleh, wearing a dark suit and speaking from behind bullet-proof glass as armed men in fatigues stood guard.

We are ready to fill the fronts with thousands of fighters and they are ready to go

- ex-president Ali Abdullah Saleh

"We are political pioneers with a solid anchor, and we have been facing conspiracies against us since 2011," he told the cheering crowd, referring to the start of protests in Sanaa that eventually led to his resignation.

Demonstrators, gathered since the early morning in Sabeen Square in central Sanaa waved flags, signs and pictures of the man who remains one of Yemen's most powerful politicians and military figures.

"With our spirit and our blood, we sacrifice for you oh Yemen!" they cheered, television footage showed.

Yemen's former President Ali Abdullah Saleh gestures to supporters as he arrives to a rally held to mark the 35th anniversary of the establishment of his General People's Congress party in Sanaa, Yemen August 24, 2017 (Reuters)

An AFP reporter in Sanaa said the Houthis had set up checkpoints at the main entrances to the city. But they did nothing to stop the demonstrators from reaching the square, where the rebels had also deployed but did not interfere with the rally.

War of words

A war of words between Saleh and Abdul Malik al-Houthi, whose rebel group have historically clashed with Saleh's troops, has escalated in the past week.

The two have publicly accused each other of treason, with Saleh hinting his allies were merely "a militia" and the rebels warning the former president he would "bear the consequences" of the insult.

The Huthis reportedly suspect Saleh has been negotiating with a Saudi-led Arab coalition that supports the Yemeni government.

Supporters of Yemen's former President Ali Abdullah Saleh rally to mark the 35th anniversary of the establishment of the General People's Congress party which is led by Saleh in Sanaa, Yemen August 24, 2017 (Reuters)

Saleh was a strong ally of Saudi Arabia from the late 1970s, when he fought the Huthis for control of Yemen, until 2014.

The Saleh camp has meanwhile accused the Houthis of aiming to consolidate their power in Sanaa.

The war between the government of Abd Rabbuh Hadi, allied with a Saudi-led Arab military coalition, and the Iran-backed rebel camp has killed more than 8,300 Yemenis since 2015 and pushed the country to the brink of famine.

More than 30 people, including civilians, were killed Wednesday in air raids on Sanaa, where the Saudi-lead coalition has been bombing the Huthis since joining the war in 2015.

A cholera outbreak has independently claimed an estimated 2,000 lives since April in Yemen.